Flameproof cellulose organic acid ester fibers and process for their preparation



i. Ma i c 13 ca sweetest 2,989,406 Patented June 20, 1961 2,989,406 FLAMEPROOF CELLULOSE ORGANIC ACID ESTER FIBERS AND PROCESS FOR THEIR PREPARATION Robert C. Harrington, Jr., and James L. Smith, Kingsport,

Tenn, assignors to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey No Drawing. Filed Dec. 12, 1957, Ser. No. 702,262 7 Claims. (Cl. 106-15) This invention relates to flame resistant compositions of matter and methods for their preparation. More particularly, this invention relates to flame resistant cellulose organic acid ester compositions containing certain amphoteric metal pyrophosphates as the flame proofing component of the compositions. Furthermore, the present invention relates to shaped articles such as synthetic filaments, fibers and textile goods made from such novel flame resistant compositions as well as to methods for incorporating the amphoteric metal pyrophosphates there- 1n.

Heretofore, various treatments have been proposed for flame proofing textiles but most have been recommended for fibers other than acetate, especially cotton. Metallic oxides of amphoteric metals, such as antimony, tin, bismuth and titanium have been recommended as flame proofing components, but they are not effective in combination with cellulose organic acid ester compositions such as cellulose acetate. Halogenated organic compounds have also been recommended, but they have the disadvantage of decomposing in storage to give hydrochloric acid which deteriorates the physical properties of the yarn and often affects dyes. Due to the fact that cotton and viscose are relatively easy to make flame resistant, there are several comparatively simple methods for treating them. But, cellulose acetate is extremely difficult to render flame resistant. A number of compounds such as brominated polymers of dag-gamma allsenyl) monochloromethane phosphate disclosed in U.S1 Patent 2,735,789 and t pi s (p;c hloroethyl)phosphate disclosed in US. Patents 2,330,251 and 2,330,254 cannot be used for some purposes due to their toxicity and adverse effect on the physical properties of the fibers.

An object of the present invention is to provide cellulose organic acid ester fibers, filaments and fabrics which have good flame proofing characteristics. A further object of this invention is to accomplish a high degree of nonflammability at a low cost. Another object of the invention is to attain the non-flammability characteristics without appreciably altering the physical characteristics and properties of the yarn such as hand, stretch, strength, and luster. A still further object is to provide a textile article such as yarn, fabric, rug, etc., made from such flame resistant cellulose acetate composition which will retain nonflammable characteristics through several launderings and after long wear. A still further object is to provide a flame resistant cellulose acetate yarn which is non-toxic. Yet another object is to provide spinning solution containing a cellulose organic acid ester and an amphoteric metal pyrophosphate in a solvent, for example, acetone. Other objects will appear hereinafter.

In accordance with the present invention, we have found that cellulose organic acid ester compositions and filaments made therefrom, may be made inflammable by incorporating therein a small amount of an amphoteric metal pyrophosphate. The amount of the amphoteric metal pyrophosphate can be varied over a substantial range, but for practical purposes, effective additions range from 0.2% to 3.0% based on the weight of the ester in the fiber and 1% by weight of the ester in the fiber is the preferred amount. The amphoteric metal pyrophosphates which may be advantageously employed are aluminum, tin, and antimony. The aluminum compound is preferred since it is most favorable from the standpoint of cost. These amphoteric metal pyrophosphate compounds may be advantageously incorporated homogeneously into the cellulose ester spinning solution and the filaments are dry spun from this solution by the wellknown dry spinning process. The yarns and fabrics made from these filaments have excellent flame proofing properties. This invention is of particular interest in connection with rug yarns, drapery yarns and doll hair fibers. These can be advantageously made from cellulose acetate filaments containing 1% of aluminum pyrophosphate.

The practice of the present invention is illustrated in the following examples:

Example 1 Aluminum pyrophosphate was prepared by mixing aqueous solutions of the soluble aluminum compound, aluminum sulfate, and a soluble pyrophosphate, tetrasodium pyrophosphate in stoichiometric proportions. Insoluble aluminum pyrophosphate Was removed by filtration.

This aluminum pyrophosphate was ground in a ball mill to a fine powder so that it would pass through the spinnerette orifices to be used to spin the filaments. It was added to a cellulose acetate spinning solution in sufficient amount to give a concentration of 1% of aluminum pyrophosphate based on the weight of the cellulose acetate. The solution was then thoroughly mixed and filtered and converted into filaments in a conventional manner such as described in H. G. Stone Patents 2,000; 047 and 2,000,048. Skeins of yarn made from a plurality of these filaments were hung in a vertical position and tested with a direct flame. Upon removal of the flame, the fire consuming the yarn would go out spontaneously. The fiber was, therefore, proved to be flame resistant. A similar skein of acetate yarn, except that it did not contain any aluminum pyrophosphate, was exposed to the identical flame test and it was consumed by flame in 10 seconds after one ignition.

Example 2 In the manner described in Example 1, aluminum pyrophosphate was added to the dry spinning solution so that the fiber spun therefrom contained 0.2% based on the weight of the cellulose acetate. Skeins of this yarn were tested for flammability and showed high resistance.

Example 3 When aluminum pyrophosphate was included in fibers at a concentration of 3.0% by the method shown in Example 1, skeins of yarn, and the fabric knitted therefrom, had the same flame resistant characteristics as those of Example 1.

Example 4 Stannous pyrophosphate was prepared by mixing aqueous solutions of stannous chloride and tetrasodium pyrophosphate in stoichiometric proportions. Insoluble stannous pyrophosphate was removed by filtration, ground to a fine powder and incorporated into the cellulose acetate spinning solution. Two different fibers were prepared, one which contained 0.75% and one 1.5% stannous pyrophosphate based on the weight of cellulose acetate. Both were nonflammable in skein and fabric forms when flame tested as described in Example 1.

Example 5 Cellulose acetate yarn containing 1.0% by weight of antimony pyrophosphate and a fabric made therefrom was nonflammable when flame tested as in Example 1.

Examples 1 to 5 were repeated using as the cellulose ester component of the composition, cellulose propionate, cellulose acetate propionate, cellulose acetate butyrate, and cellulose acetate phthalate and similar fire protection was imparted to the yarn and fabrics made therefrom.

These yarns are readily dyeable with the usual acetate dyes, the presence of the amphoteric metal pyrophosphate does not affect dyeability or color fastness. Neither does the use or the presence of these pyrophosphates in the yarn cause toxicity problems or adverse effect on the physical properties of the fibers.

Example 6 A dry spinning solution consisting of 29.0% cellulose acetate, 1% aluminum pyrophosphate, 1.75% water and 68.25% acetone was spun into substantially perfect U- shaped cross-section filaments of a denier of 21.4 using the apparatus and general operation described in connection with FIG. 1 of Smith et al. patent application S.N. 675,392, filed July 31, 1957, entitled Process and Apparatus for Dry Spinning Synthetic Filaments and Fibers and Products Produced Therefrorn. A pile mg was made from yarn comprising a multiplicity of these filaments. The rug was flame tested as described in Example 1, and found suitable for general use in a house from the standpoint of nonflammability.

We claim:

1. A flame resisting composition essentially consisting of a cellulose organic acid ester selected from the group consisting of cellulose acetate, cellulose propionate, cel lulose acetate propionate, cellulose acetate butyrate and cellulose acetate phthalate and as a fiameproofing component from 0.2 to 3% by weight of the ester of aluminum pyrophosphate.

2. Flame resisting fibers essentially consisting of a cellulose organic acid ester selected from the group consisting of cellulose acetate, cellulose propionate, cellulose acetate propionate, cellulose acetate butyrate and cellulose acetate phthalate and as a flatneproofing component from 0.2 to 3% by weight of the ester of aluminum pyrophosphate.

3. Flame resisting fibers essentially consisting of cellulose acetate and from 0.2 to 3% by weight of the cellulose acetate of aluminum pyrophosphate.

4. Flame resisting fibers essentially consisting of cellulose acetate and 1% by weight of the cellulose acetate of aluminum pyrophosphate.

5. A fabric containing as fireproofing elements a plurality of fibers consisting essentially of cellulose acetate and 0.2 to 3% by weight of the cellulose acetate of aluminum pyrophosphate.

6. A pile rug constructed of fibers consisting essentially of cellulose acetate and 0.2 to 3% by weight of the cellulose acetate of aluminum pyrophosphate.

7. A dry spinning solution for the production of flame resistant cellulose organic acid ester yarn consisting essentially of an ester selected from the group consisting of cellulose acetate, cellulose propionate, cellulose acetate propionate, cellulose acetate butyrate and cellulose acetate phthalate dissolved in a solvent for the ester and from 0.2 to 3.0% by weight of the ester of aluminum pyrophosphate.

References Cited in the file of this patent ,,,.UNITED STATES PATENTS 1,538,859 Lindsay May 19, 1925 2,052,558 Dreyfus Sept. 1, 1936 2,202,124 Tattersall May 28, 1940 2,464,342 Pollack et al. Mar. 15, 1949' 2,779,691 Loukamsky Jan. 29, 1957 2,876,117 Jackson et a1. Mar. 3, 1959 2,876,118 Jackson Mar. 3, 1959 FOREIGN PATENTS 731,176 Great Britain June 1, 1955 748,165 Great Britain Apr. 25, 1956 

1. A FLAME RESISTING COMPOSITION ESSENTIALLY CONSISTING OF A CELLULOSE ORGANIC ACID ESTER SELECTED FROM THE GROUP CONSISTING OF CELLULOSE ACETATE, CELLULOSE PROPIONATE, CELLULOSE ACETATE PROPIONATE, CELLULOSE ACETATE BUTYRATE AND CELLULOSE ACETATE PHTHALATE AND AS A FLAMEPROOFING COMPONENT FROM 0.2 TO 3% BY WEIGHT OF THE ESTER OF ALUMINUM PYROPHOSPHATE. 